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rails--rails/activerecord/lib/active_record/result.rb
Yves Senn 428d47adfe applies new doc guidelines to Active Record.
The focus of this change is to make the API more accessible.
References to method and classes should be linked to make it easy to
navigate around.

This patch makes exzessiv use of `rdoc-ref:` to provide more readable
docs. This makes it possible to document `ActiveRecord::Base#save` even
though the method is within a separate module
`ActiveRecord::Persistence`. The goal here is to bring the API closer to
the actual code that you would write.

This commit only deals with Active Record. The other gems will be
updated accordingly but in different commits. The pass through Active
Record is not completely finished yet. A follow up commit will change
the spots I haven't yet had the time to update.

/cc @fxn
2015-10-14 17:40:00 +02:00

132 lines
3.2 KiB
Ruby

module ActiveRecord
###
# This class encapsulates a result returned from calling
# {#exec_query}[rdoc-ref:ConnectionAdapters::DatabaseStatements#exec_query]
# on any database connection adapter. For example:
#
# result = ActiveRecord::Base.connection.exec_query('SELECT id, title, body FROM posts')
# result # => #<ActiveRecord::Result:0xdeadbeef>
#
# # Get the column names of the result:
# result.columns
# # => ["id", "title", "body"]
#
# # Get the record values of the result:
# result.rows
# # => [[1, "title_1", "body_1"],
# [2, "title_2", "body_2"],
# ...
# ]
#
# # Get an array of hashes representing the result (column => value):
# result.to_hash
# # => [{"id" => 1, "title" => "title_1", "body" => "body_1"},
# {"id" => 2, "title" => "title_2", "body" => "body_2"},
# ...
# ]
#
# # ActiveRecord::Result also includes Enumerable.
# result.each do |row|
# puts row['title'] + " " + row['body']
# end
class Result
include Enumerable
IDENTITY_TYPE = Type::Value.new # :nodoc:
attr_reader :columns, :rows, :column_types
def initialize(columns, rows, column_types = {})
@columns = columns
@rows = rows
@hash_rows = nil
@column_types = column_types
end
def length
@rows.length
end
def each
if block_given?
hash_rows.each { |row| yield row }
else
hash_rows.to_enum { @rows.size }
end
end
def to_hash
hash_rows
end
alias :map! :map
alias :collect! :map
# Returns true if there are no records.
def empty?
rows.empty?
end
def to_ary
hash_rows
end
def [](idx)
hash_rows[idx]
end
def last
hash_rows.last
end
def cast_values(type_overrides = {}) # :nodoc:
types = columns.map { |name| column_type(name, type_overrides) }
result = rows.map do |values|
types.zip(values).map { |type, value| type.deserialize(value) }
end
columns.one? ? result.map!(&:first) : result
end
def initialize_copy(other)
@columns = columns.dup
@rows = rows.dup
@column_types = column_types.dup
@hash_rows = nil
end
private
def column_type(name, type_overrides = {})
type_overrides.fetch(name) do
column_types.fetch(name, IDENTITY_TYPE)
end
end
def hash_rows
@hash_rows ||=
begin
# We freeze the strings to prevent them getting duped when
# used as keys in ActiveRecord::Base's @attributes hash
columns = @columns.map { |c| c.dup.freeze }
@rows.map { |row|
# In the past we used Hash[columns.zip(row)]
# though elegant, the verbose way is much more efficient
# both time and memory wise cause it avoids a big array allocation
# this method is called a lot and needs to be micro optimised
hash = {}
index = 0
length = columns.length
while index < length
hash[columns[index]] = row[index]
index += 1
end
hash
}
end
end
end
end